In electronic data networks, there is often a need to discern or discover the topology of the networks, for example links between nodes in the networks formed via interfaces of the nodes and subnets between the nodes.
U.S. Pat. No. 6,172,986 discloses a mobile node moving from a first IP (Internet Protocol) network having a first kind of IP to a second IP network having a second kind of IP, in a network system. When the mobile node communicates a message with other nodes on the first network after its movement, a header for the movement containing both home and foreign addresses in the first kind of IP is added to a header containing home and foreign addresses in the second kind of IP, and the headers are added to the message.
U.S. Pat. No. 6,188,784 discloses an apparatus for handling communications from both IPv4 and IPv6 terminals.
U.S. Pat. No. 6,038,233 discloses a translator for coupling a first network such as an internet protocol version 4 (IPv4) and a second network such as an internet protocol version 6 (IPv6) having different addressing architectures for IP addresses.